JPH09130013A - Fabrication of printed wiring board and substrate for multiple patterns - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent enlargement and spreading of crack of resin layer resulting from molding of metal dies. SOLUTION: A substrate 1 for multiple pattern having a plurality of product areas 4 in which the conductor patterns are formed is fabricated. In this case, a crack preventing wall is previously formed of a metal material in the region R2 outside the pattern forming region R1 in the product areas 4. The crack preventing wall is for example dummy conductor patterns 13, 14. Thereafter, a plurality sheets of the printed wiring boards 2 can be fabricated from one substrate 1 by cutting the board along the external line of the product areas 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board and a multi-piece board for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a printed wiring board, a method of obtaining a plurality of products from a single substrate on which a conductor pattern is formed (a so-called multi-chip method)
Has been implemented. An example of a conventional method for manufacturing a printed wiring board will be introduced below with reference to FIGS. 7 and 8. The additive process is taken as an example here.

First, when manufacturing the printed wiring board 31, a base material 32 is prepared. This base material 32 is used for a plurality of product parts 33 to be products (printed wiring board 31) later.
And a non-product part 34 and a connecting part 35 that connects the non-product parts 34 and 33. The base material 32
On one or both sides of the inner layer conductor pattern 3 beforehand
6 is patterned. Next, an adhesive for additive is applied on the base material 32 to roughen the surface of the adhesive layer 37. Then, after forming a permanent resist 38 on the upper surface of the adhesive layer 37, the outer layer conductor pattern 39 is formed by electroless plating on the resist non-forming portion. After that, a solder resist 40 that covers the formed outer layer conductor pattern 39 is formed. Then, the above-mentioned multi-chip board 41 is finally divided along the outline using a cutting means such as a die 42, and the side end faces are ground as necessary. As a result, the multi-piece board 41 is made into individual products. As described above, a plurality of printed wiring boards 31 can be obtained from one multi-piece board 41.

[0004]

However, the conventional method for manufacturing the printed wiring board 31 has the following problems.

The resin used for the printed wiring board 31, that is, the resin forming the solder resist 40 and the adhesive layer 37 is relatively fragile. Therefore, the mold 42
If a large stress is applied at the time of dividing the substrate due to the cracks, cracks C1 will occur in the resin layer. Many such cracks C1 are generated around the contour line on the pressing surface side of the die 42, particularly in the vicinity of the bent portion (that is, the corner portion) of the contour line or the connecting portion 35. Was empirically known. Further, when such a crack C1 spreads to the pattern forming region and also extends in the thickness direction, the outer layer conductor pattern 39-the inner layer conductor pattern 36.
There is a problem that it causes an interlayer short circuit between them (see FIGS. 7 (b) and 8). Further, even if a short circuit failure does not occur, there is a problem that problems such as deterioration of insulation resistance easily occur. That is, in the conventional manufacturing method,
It was difficult to obtain the printed wiring board 31 with high reliability.

From the above, in the past, in order to avoid the occurrence of the crack C1 itself, there was no choice but to perform the substrate dividing step by using the router or the like instead of the mold 42. However, since router processing is more expensive and requires more work time than die processing, it cannot be said to be preferable from the viewpoint of cost reduction and production efficiency.

The present invention has been made to solve the above problems, and a first object of the present invention is to reliably prevent a crack in a resin layer caused by mold molding from spreading and spreading to a pattern forming region. It is to provide a method of manufacturing a printed wiring board that can be manufactured. A second object of the present invention is to
It is to solve the problems relating to the cracks and achieve cost reduction and production efficiency improvement.

[0008]

In order to solve the above problems, according to the invention of claim 1, a multi-piece board having a plurality of product parts on which a conductor pattern is formed is provided with an outer shape of the product part. By dividing along the line, in the method of manufacturing a plurality of printed wiring boards from the substrate, after forming a crack prevention wall made of a metal material in a region on the outer edge side of the pattern formation region in the product part The gist of the method is a method of manufacturing a printed wiring board for dividing the board.

According to a second aspect of the present invention, in the first or second aspect, the crack prevention wall is formed over substantially the entire outer edge of the product portion. Claim 3
According to the invention described in claim 2, in claim 2, the crack prevention wall is a dummy conductor pattern which is simultaneously formed at the time of pattern formation.

According to a fourth aspect of the present invention, a plurality of product parts having conductor patterns are formed, and a plurality of printed wiring boards can be obtained by dividing along the outline of the product parts. The gist of the multi-divided substrate is a multi-divided substrate in which a crack prevention wall made of a metal material is formed in a region on the outer edge side of the pattern forming region in the product portion.

Hereinafter, the "action" of the present invention will be described. According to the invention described in claims 1 and 4, a crack prevention wall made of a metal material is formed in a region on the outer edge side of the pattern forming region in the product portion. Therefore, in the area between the outline of the product part and the pattern forming area, there is a structure in which a structure that is more resistant to stress than the resin layer is interposed. If the dividing step is performed in this state, even if a crack is generated in the vicinity of the outline, its expansion is prevented by the crack prevention wall. That is, since the stress can be concentrated on the crack prevention wall, the crack does not spread to the pattern formation region. Therefore, short-circuit defects between layers and deterioration of insulation resistance are surely avoided. Then, by solving the problem regarding the expansion and spread of cracks in this way, it becomes possible to divide the substrate by a die processing that is inexpensive and does not require a long working time. Therefore, cost reduction and improvement in production efficiency can be achieved as compared with the case where division is performed by router processing.

Also, the crack prevention wall, if it is not necessary, can be easily removed by a grinding process which is usually carried out after the dividing process. Therefore, it is also possible to manufacture the final product without leaving a crack prevention wall. Of course, the resin layer having cracks can be removed at the same time during the grinding process. Therefore, the appearance of the obtained printed wiring board is also improved.

In addition to the function of the invention described in claim 1, according to the invention described in claim 2, since the crack prevention wall is formed over substantially the entire outer edge of the product portion, the pattern formation region is formed. It is almost completely surrounded by the crack prevention wall. For this reason, the wraparound of cracks is also prevented, and the expansion of cracks to the pattern formation region is more reliably prevented.

According to the invention of claim 3 in addition to the functions of the inventions of claims 1 and 2, the dummy conductor pattern serving as the crack prevention wall is provided with existing equipment for pattern formation. Can be formed using a process. Therefore, as compared with the case where the crack prevention wall is formed by using a special device or the like in another step, it is possible to more reliably reduce the cost and improve the production efficiency.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in a method for manufacturing a multilayer printed wiring board 2 using a multi-piece board 1 will be described in detail with reference to FIGS.

As shown in FIG. 1 and FIG. 2, the base material 3 which constitutes the multi-piece board 1 is composed of a plurality of product parts 4 which are to be products (that is, the multilayer printed wiring board 2) later, and later. It is composed of a non-product portion 5 that is cut off and a connecting portion 6 that connects the non-product portions 5 and 4. In addition, the multi-piece substrate 1 of the present embodiment has three different shapes and sizes.
There are two product parts 4.

As shown in FIG. 3 (a), the substrate 3
Inner-layer conductor patterns 7 made of electroless copper plating are formed in the pattern forming regions R1 on both surfaces of. An insulating layer 8 is formed on the upper surface of the inner layer conductor pattern 7, and an adhesive layer 9 is further formed on the upper surface thereof. The surface layer of the adhesive layer 9 is a roughened surface 9a having many fine anchor recesses. A permanent resist 10 is formed on the upper surface of the roughened surface 9a. Further, an outer conductor pattern 11 made of electroless copper plating is formed on a portion of the pattern forming region R1 where the permanent resist 10 is not formed. The inner layer conductor pattern 7 and the outer layer conductor pattern 11 are electrically connected by via holes or through holes (not shown). Then, the permanent resist 10 and the outer conductor pattern 1 are formed.
1 is entirely covered with a solder resist 12.

As shown in FIG. 1 to FIG. 3, in the multi-chip board 1, a region R2 on the outer edge side of the pattern forming region R1 in the product portion 4 (hereinafter, simply outer edge region R2
Call. ), Dummy conductor patterns 13 and 14 are formed as crack prevention walls. The dummy conductor patterns 13 and 14 are so called because they do not particularly contribute to conduction. In the case of the present embodiment, the two dummy conductor patterns 13 and 14 are in parallel relationship with each other, and they are simultaneously formed during pattern formation. Further, these dummy conductor patterns 13 and 14 are formed over the entire outer edge of the product portion 4, and the pattern forming region R1
Is completely surrounded from the outside.

The thickness of the dummy conductor patterns 13 and 14 is preferably about 20 μm or more, and the thickness of this range is effective. If it is too thin, not only will it be difficult to form, but it may not be possible to reliably prevent the crack C1. The distance from the end face of the product portion 4 to the dummy conductor pattern 13 on the outer peripheral side is preferably 0.1 mm or more. If this distance is less than 0.1 mm, the effect of preventing the crack C1 may be halved in some cases.

In consideration of the above circumstances, in the present embodiment,
The thickness of the dummy conductor patterns 13 and 14 is set to 100 μm, and the distance from the end face is set to 0.4 mm. Further, the space between the two dummy conductor patterns 13 and 14 is set to 100 μm.

Next, a method of manufacturing the multilayer printed wiring board 2 using the multi-chip board 1 will be described in order. First,
A copper clad laminate obtained by sticking copper foils on both sides is prepared, and a pattern is formed according to a conventionally known subtractive process or the like. As a result, first, the inner layer conductor pattern 7 is formed on the base material 3. Next, the product part 4, the non-product part 5 and the connecting part 6 are formed by punching out a predetermined part of the base material 3. At this time, since the resin layer is not yet present on the base material 3, there is no need to worry about the occurrence of the crack C1.

Next, the insulating layer forming varnish is applied and cured to form the insulating layer 8 on both surfaces of the base material 3. At this time, the inner layer conductor pattern 7 is covered with the insulating layer 8. Next, an adhesive agent for additive is applied onto the insulating layer 8 and cured to form an adhesive layer 9 on both sides of the base material 3. The additive adhesive is a resin matrix that is hardly soluble in an acid or an oxidant, and a resin filler that is easily soluble in the acid or the oxidant is dispersed in the resin matrix. Therefore, when the adhesive layer 9 is treated with an acid or an oxidizing agent (that is, a roughening treatment is performed), the resin filler is selectively dissolved to form a roughened surface 9a on the surface layer.

Then, a varnish of a photosensitive resin is applied to the upper surface of the roughened adhesive layer 9, and the varnish is dried. Further, the permanent resist 10 is formed by performing exposure and development. After that, the outer layer conductor pattern 11 is patterned by depositing electroless copper plating on the non-resist formation portion. Incidentally, through this step, the dummy conductor patterns 13 and 14 are simultaneously formed. Therefore, the dummy conductor patterns 13 and 14 are made of the same material and have the same thickness as the outer layer conductor pattern 11. Next, the solder resist 12 is formed, thereby covering the outer layer conductor pattern 11 entirely. As a result of the above, a multi-piece substrate 1 as shown in FIG. 1 is manufactured.

In the subsequent substrate dividing step, after fixing a large number of substrates 1 for connecting, each connecting portion 6 is punched out using a mold 15. As a result, as shown in FIGS. 3B and 4, the product portion 4 is divided along the outline thereof. Then, the side end surface of the divided product portion 4 is ground to remove unnecessary substances such as burrs of the resin layer on the side end surface. As described above, a plurality of multi-layer printed wiring boards 2 can be obtained from one multi-layer board 1.

The characteristic effects of this embodiment will be listed below. (A) According to this embodiment, dummy conductor patterns 13 and 14 are formed as crack prevention walls in the outer edge region R2 on the outer edge side of the pattern formation region R1 in the product portion 4. Therefore, in the area between the outline of the product portion 4 and the pattern forming area R1, there is a structure in which a structure having a higher stress than the resin layers such as the solder resist 12 and the adhesive layer 9 is interposed. If the substrate dividing step is performed in this state, even if the crack C1 occurs near the outline, the expansion is blocked by the dummy conductor patterns 13 and 14 (see FIGS. 3B and 4). That is, the stress applied during division is applied to the dummy conductor pattern 1
Since it can be concentrated on the portions 3 and 14, the crack C1 does not spread to the pattern formation region R1. Therefore, short-circuit defects between layers and deterioration of insulation resistance are surely avoided. Therefore, according to the present embodiment,
It is possible to obtain a large number of highly reliable multilayer printed wiring boards 2.

(B) Then, as described above, the crack C1
By solving the problem of enlargement / spreading, it is possible to divide the multi-piece board 1 by processing with the die 15 which is inexpensive and does not require much working time. Therefore, as compared with the case where the division is performed by, for example, router processing, the cost can be reduced and the production efficiency can be improved.

(C) The present embodiment is characterized in that the dummy conductor patterns 13 and 14 are formed in the region close to the outline. Therefore, the dummy conductor pattern 1
3, 14 can be easily removed, if not required, by going through a grinding step performed after the substrate dividing step. Therefore, it is possible to manufacture the multilayer printed wiring board 2 as the final product without leaving the dummy conductor patterns 13 and 14. Of course, the resin layer in which the crack C1 is generated can be removed at the same time during the grinding step. Therefore, the appearance of the obtained multilayer printed wiring board 2 is also improved.

(D) According to this embodiment, since the dummy conductor patterns 13 and 14 are formed over the entire outer edge of the product portion 4, the pattern forming region R1 is completely formed by the dummy conductor patterns 13 and 14. Be surrounded. Therefore, the crack C1 in the pattern formation region R1
The expansion is being blocked more reliably.

(E) According to this embodiment, the dummy conductor patterns 13 and 14 which are the crack prevention walls are formed at the same time when the outer layer conductor pattern 11 is formed. That is, the dummy conductor patterns 13 and 1
4 can be formed using existing equipment and processes for pattern formation. Therefore, as compared with the case where it is formed by using a special device or the like in another step, it is possible to more reliably reduce the cost and improve the production efficiency. In this embodiment, the pattern forming method is a simple plating method, and the plating metal is inexpensive copper, which is extremely advantageous in reducing the cost.

(F) In this embodiment, two dummy conductor patterns 13 and 14 are formed in parallel with each other. Therefore, even if the expansion of the crack C1 cannot be prevented by the dummy conductor pattern 13 on the outer peripheral side, it can be prevented by the dummy conductor pattern 14 on the inner peripheral side. That is, the dummy conductor pattern 13,
The expansion of the crack C1 can be prevented more reliably than in the case where there is only one.

The present invention can be modified as follows, for example. (1) The dummy conductor patterns 13 and 14 are not limited to the electroless plating layer and may be an electrolytic plating layer.
Furthermore, the dummy conductor patterns 13 and 14 do not have to be a plating layer formed by a plating method, and may be, for example, a metal layer formed by a printing method or a sputtering method that is performed separately from the pattern formation. Further, the metal species is not limited to copper, and for example, gold, silver, nickel, tungsten, molybdenum, iron, chromium, zinc, titanium or the like can be selected. However, as shown in the embodiment, the selection of the plating method and the selection of copper are extremely preferable for cost reduction and improvement of production efficiency.

(2) In another example 1 shown in FIG. 5, unlike the continuous embodiment, the dummy conductor patterns 21,
22 is formed discontinuously. Specifically, the dummy conductor patterns 21 and 22 are partially formed in the vicinity of the corner portion and the connecting portion 6, that is, centered on the crack-prone portion. Even in this case, it is possible to prevent the crack C1 from expanding to the pattern forming region R1. However, if it is formed over the entire outer edge as in the above-described embodiment, there is an advantage that the crack C1 can be prevented from wrapping around. Therefore,
In terms of surely preventing the expansion of crack C1,
The embodiment is more preferable, and the other example 1 is based on it.

(3) In another example 2 shown in FIG. 6, one continuous dummy conductor pattern 25 over the entire outer edge,
Two non-continuous short dummy conductor patterns 26, 27
Are formed. The two short dummy conductor patterns 26 and 27 are arranged in the crack-prone portion. As described above, the number of cracked portions may be increased.

(4) Dummy conductor patterns 13, 14 ...
Is preferably provided not only on the pressing surface of the multi-piece board 1 but also on the non-pressing surface. In addition, the dummy conductor patterns 13 and 14
Is preferably provided not only on the same surface as the outer layer conductor pattern 11 but also on the same surface as the inner layer conductor pattern 7. In the above case, the existence ratio of the dummy conductor patterns 13, 14 ... Is increased, and the action of preventing the expansion of the crack C1 is further improved.

Here, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below together with their effects. (1) The crack prevention wall is formed on at least a crack-prone portion at an outer edge of the product portion.
The method for manufacturing a printed wiring board according to claim 4 (or the substrate for multi-piece wiring according to claim 4).

(2) The method for manufacturing a printed wiring board according to claim 2, wherein the crack prevention wall is a dummy conductor pattern formed at the same time when the outer layer conductor pattern is formed by electroless copper plating. The substrate for multi-chip forming according to claim 4. By doing so, it is possible to further reduce the cost and improve the production efficiency by selecting the plating method and copper.

(3) The method for manufacturing a printed wiring board according to claim 3 (or the substrate for multi-division according to claim 4), characterized in that a plurality of the dummy conductor patterns are provided. By doing this, one dummy conductor pattern
The expansion of cracks can be prevented more reliably than in the case where only a book is provided.

The technical terms used in the present specification are defined as follows. "Adhesive for Additive: A resin matrix in which an easily soluble resin filler is dispersed in an acid or an oxidizing agent in a resin matrix which is hardly soluble in an acid or an oxidizing agent."

[0039]

As described in detail above, according to the invention described in claims 1 to 3, it is possible to surely prevent the crack of the resin layer caused by the mold molding from spreading and spreading to the pattern forming region. It is possible to provide a method for manufacturing a printed wiring board that can be used. At the same time, cost reduction and improvement in production efficiency can be achieved.

According to the second aspect of the present invention, it is possible to more reliably prevent the crack from spreading and spreading. According to the invention described in claim 3, it is possible to surely reduce the cost and improve the production efficiency.

According to the fourth aspect of the present invention, there is provided a multi-dividing substrate which can surely prevent the cracks of the resin layer caused by molding from spreading and spreading to the pattern forming region. be able to.

[Brief description of the drawings]

FIG. 1 is a plan view showing a multi-chip board (before division) according to an embodiment.

FIG. 2 is also a partially enlarged plan view showing the multi-chip substrate (before division).

FIG. 3A is a partial schematic cross-sectional view of the same multi-substrate (before division), and FIG. 3B is a partial schematic cross-sectional view of the same substrate (after division).

FIG. 4 is a partially enlarged plan view showing the multi-layer substrate (after division).

FIG. 5 is a plan view showing a multi-chip substrate (before division) of another example 1.

FIG. 6 is a plan view showing a multi-chip substrate (before division) of Modification 2.

7A is a partial schematic cross-sectional view showing a conventional multi-chip board (before division), and FIG. 7B is a partial schematic cross-sectional view of the same board (after division).

FIG. 8 is a partially enlarged plan view showing a conventional multi-chip substrate (after division).

[Explanation of symbols]

1 ... substrate for multi-piece printing, 2 ... (multilayer) printed wiring board,
4 ... Product part, 7 ... Inner layer conductor pattern, 11 ... Outer layer conductor pattern, 13, 14, 21, 22, 25, 26, 27 ...
Dummy conductor pattern as crack prevention wall, R1 ...
Pattern forming area, R2 ... Outer edge area.

Claims (4)

[Claims] 1. A method of manufacturing a plurality of printed wiring boards from the substrate by dividing a multi-grid board having a plurality of product parts on which conductor patterns are formed along the outline of the product part. In, in the region on the outer edge side of the pattern forming region in the product portion, after forming a crack prevention wall made of a metal material,
A method for manufacturing a printed wiring board for dividing the substrate. 2. The method for manufacturing a printed wiring board according to claim 1, wherein the crack prevention wall is formed over substantially the entire outer edge of the product portion. 3. The method for manufacturing a printed wiring board according to claim 1, wherein the crack prevention wall is a dummy conductor pattern that is simultaneously formed during pattern formation. 4. A large number of printed wiring boards having a plurality of product parts having a conductor pattern formed thereon and dividing the product parts along the outline of the product parts to obtain a plurality of printed wiring boards. A substrate for multi-piece formation, wherein a crack prevention wall made of a metal material is formed in a region of the product portion on the outer edge side of the pattern formation region.